Process for hydroformylation of olefins using Pt and bromine

ABSTRACT

Process for hydroformylation of olefins using Pt and bromine.

The present invention relates to a process for hydroformylation ofolefins using Pt and bromine.

C. Botteghi et al., Journal of Molecular Catalysis A: Chemical 200,(2003), 147-156 describes the use of Pt(Xantphos)Cl₂ forhydroformylation of 2-tosyloxystyrene.

The problem addressed by the present invention is that of providing anovel hydroformylation process. The process here is to afford anincreased yield compared to the process known from the prior art usingPt(Xantphos)Cl₂.

This problem is solved by a process according to claim 1.

Process comprising the process steps of:

a) initially charging an olefin;

b) adding a compound of formula (I):

where R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸ are selected from: —H,—(C₁-C₁₂)-alkyl, —(C₆-C₂₀)-aryl;

and, if R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸ are —(C₆-C₂₀)-aryl, the aryl ringmay have substituents selected from: —(C₁-C₁₂)-alkyl, —O—(C₁-C₁₂)-alkyl;

c) adding a Pt compound capable of forming a complex;

d) adding a bromine compound;

e) feeding in CO and H₂;

f) heating the reaction mixture from steps a) to e), to convert theolefin to an aldehyde.

In this process, process steps a) to e) can be effected in any desiredsequence. Typically, however, CO and H₂ are added after the co-reactantshave been initially charged in steps a) to d).

It is possible here for process steps c) and d) to be effected in onestep, by adding PtBr₂. In a preferred variant of the process, the Ptcompound and the bromine compound are added in one step, by addingPtBr₂.

The expression (C₁-C₁₀-alkyl encompasses straight-chain and branchedalkyl groups having 1 to 12 carbon atoms. These are preferably(C₁-C₈)-alkyl groups, more preferably (C₁-C₆)-alkyl, most preferably(C₁-C₄)-alkyl.

Suitable (C₁-C₁₂)-alkyl groups are especially methyl, ethyl, propyl,isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 2-pentyl,2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 1,1-dimethylpropyl,2,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 2-hexyl, 2-methylpentyl,3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl,2,2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl,3,3-dimethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl,1-ethylbutyl, 1-ethyl-2-methylpropyl, n-heptyl, 2-heptyl, 3-heptyl,2-ethylpentyl, 1-propylbutyl, n-octyl, 2-ethylhexyl, 2-propylheptyl,nonyl, decyl.

The expression (C₆-C₂₀)-aryl encompasses mono- or polycyclic aromatichydrocarbyl radicals having 6 to 20 carbon atoms. These are preferably(C₆-C₁₄)-aryl, more preferably (C₆-C₁₀)-aryl.

Suitable (C₆-C₂₀)-aryl groups are especially phenyl, naphthyl, indenyl,fluorenyl, anthracenyl, phenanthrenyl, naphthacenyl, chrysenyl, pyrenyl,coronenyl. Preferred (C₆-C₂₀)-aryl groups are phenyl, naphthyl andanthracenyl.

In one variant of the process, R², R³, R⁵, R⁶, R⁷, R⁸ are selected from:—(C₁-C₁₂)-alkyl, —(C₆-C₂₀)-aryl.

In one variant of the process, R⁵, R⁶, R⁷, R⁸ are —(C₆-C₂₀)-aryl.

In one variant of the process, R⁵, R⁶, R⁷, R⁸ are -Ph.

In one variant of the process, R² and R³ are —(C₁-C₁₂)-alkyl.

In one variant of the process, R² and R³ are —CH₃.

In one variant of the process, R¹ and R⁴ are each —H.

In one variant of the process, the compound (I) has the structure (1):

In one variant of the process, the Pt compound is selected from:Pt(II)Br₂, Pt(IV)Br₄, diphenyl(1,5-COD)Pt(II), Pt(II)(acac)₂,Pt(0)(PPh₃)₄, Pt(0)(DVTS) solution (CAS: 68478-92-2),Pt(0)(ethylene)(PPh₃)₂, Pt(II)Br₂(COD), tris(benzylideneacetone)Pt(0),Pt(II)(OAC)₂ solution, Pt(0)(t-Bu)₂, Pt(II)(COD)Me₂, Pt(II)(COD)I₂,Pt(IV)IMe₃, Pt(II)(hexafluoroacetylacetonate)₂.

In one variant of the process, the Pt compound is selected from:Pt(II)Br₂, Pt(II)(acac)₂.

In one variant of the process, the bromine compound is selected from:alkali metal halide, alkaline earth metal halide, NH₄X, alkylammoniumhalide, dialkyl halide, trialkyl halide, tetraalkyl halide,cycloalkylammonium halide.

In one variant of the process, the bromine compound is selected from:Pt(II)Br₂, LiBr.

In one variant of the process, the bromine compound is added in anamount in the range of 0.1 to 10, measured in equivalents based on Pt.

In one variant of the process, this process comprises the additionalprocess step e′): e′) adding a solvent.

In one variant of the process, the solvent is selected from: THF, DCM,ACN, DMF, toluene, texanol, pentane, hexane, octane, isooctane, decane,dodecane, cyclohexane, benzene, xylene, Marlotherm, propylene carbonate,MTBE, diglyme, triglyme, diethyl ether, dioxane, isopropanol,tert-butanol, isononanol, isobutanol, isopentanol, ethyl acetate.

In one variant of the process, the solvent is selected from: THF, DCM,ACN, DMF, toluene, Texanol.

In one variant of the process, CO and H₂ are fed in at a pressure in arange from 1 MPa (10 bar) to 6 MPa (60 bar).

In one variant of the process, CO and H₂ are fed in at a pressure in arange from 1 MPa (20 bar) to 6 MPa (50 bar).

In one variant of the process, the mixture is heated at a temperature inthe range from 25° C. to 150° C.

In one variant of the process, the mixture is heated at a temperature inthe range from 30° C. to 130° C.

In one variant of the process, the olefin is selected from: ethene,propene, 1-butene, cis- and/or trans-2-butene, isobutene, 1,3-butadiene,1-pentene, cis- and/or trans-2-pentene, 2-methyl-1-butene,3-methyl-1-butene, 2-methyl-2-butene, hexene, tetramethylethylene,heptene, 1-octene, 2-octene, di-n-butene, or mixtures thereof.

The invention shall be elucidated in more detail hereinbelow withreference to working examples.

EXPERIMENTAL DESCRIPTION

A vial was charged with PtX₂ (X=halogen), ligand, and an oven-driedstirrer bar. The vial is then sealed with a septum (PTFE-coatedstyrene-butadiene rubber) and phenolic resin cap. The vial is evacuatedand refilled with argon three times. Toluene and olefin were added tothe vial using a syringe. The vial was placed in an alloy plate, whichwas transferred to an autoclave (300 ml) of the 4560 series from ParrInstruments under an argon atmosphere. After purging the autoclave threetimes with CO/H₂, the synthesis gas pressure was increased to 40 bar atroom temperature. The reaction was conducted at 120° C. for 20 h/18 h.On termination of the reaction, the autoclave was cooled to roomtemperature and cautiously decompressed. Yield and selectivity weredetermined by GC analysis.

Hydroformylation of 1-octene

Reaction conditions:

20 mmol of 1-octene, 1.0 mol % Pt, 2.2 equivalents of Xantphos (1),solvent: toluene, p(CO/H₂): 40 bar, T: 120° C., t: 20 h.

Yields:

PtBr₂: 99%

PtCl₂: 30%

Variation of the Halogen (2-octene)

Reaction conditions:

20 mmol of 2-octene, 1.0 mol % Pt, 1.1 equivalents of Xantphos (1),solvent: toluene, p(CO/H₂): 40 bar, T: 120° C., t: 20 h.

Yields:

PtBr₂: 99%

PtCl₂: 16%

Variation of the Halogen (1-octene)

Reaction conditions:

10.0 mmol of 1-octene, 0.1 mol % PtX₂, 2.2 equivalents of ligand,solvent: toluene, p(CO/H₂): 40 bar, T: 120° C., t: 20 h.

Yields:

Ligand Halogen Yield [%]

Br/Cl 97/5

Variation of the Ligand and of the Halogen

Reaction conditions:

1.0 mmol of 2-octene, 0.5 mol % PtX₂, 2.0 equivalents of ligand,solvent: toluene, p(CO/H₂): 40 bar, T: 120° C., t: 18 h.

Yields:

Ligand Halogen Yield [%]

Br/Cl 85/<1

Br/Cl 81/<1

Variation of the Equivalents and of the Halogen

Reaction conditions:

1.0 mmol of 1-octene, 1.0 mol % Pt(acac)₂, LiX (X=halogen), 2.2equivalents of Xantphos (1), solvent: toluene, p(CO/H₂): 40 bar, T: 120°C., t: 20 h.

Equivalents of LiX X Yield [%] 0.5 Br 68 2.0 Br 71 1.5 Cl 0 4.0 Cl 0

As the experimental results show, the problem is solved by the processaccording to the invention.

The invention claimed is:
 1. A process comprising the process steps of:a) initially charging an olefin; b) adding a compound of formula (I):

where R¹, R², R³, R⁴, R⁵, R⁶, R⁷ and R⁸ are selected from: —H,—(C₁-C₁₂)-alkyl or —(C₆-C₂₀)-aryl; and, if R¹, R², R³, R⁴, R⁵, R⁶, R⁷and R⁸ are —(C₆-C₂₀)-aryl or the aryl ring may have substituentsselected from: —(C₁-C₁₂)-alkyl or —O—(C₁-C₁₂)-alkyl; c) adding a Ptcompound capable of forming a complex; d) adding a bromine compound inan amount in the range of 0.1 to 10, measured in equivalents based onPt; e) feeding in CO and H₂; f) heating the reaction mixture from stepsa) to e), to convert the olefin to an aldehyde.
 2. The process accordingto claim 1, where R², R³, R⁵, R⁶, R⁷ and R⁸ are selected from:—(C₁-C₁₂)-alkyl or —(C₆-C₂₀)-aryl.
 3. The process according to claim 1,where R⁵, R⁶, R⁷ and R⁸ are —(C₆-C₂₀)-aryl.
 4. The process according toclaim 1, where R² and R³ are —(C₁-C₁₂)-alkyl.
 5. The process accordingto claim 1, where R¹ and R⁴ are each —H.
 6. The process according toclaim 1, wherein the compound (I) has the structure (1):


7. The process according to claim 1, wherein the Pt compound is selectedfrom: Pt(II)Br₂, Pt(IV)Br₄, diphenyl(1,5-COD)Pt(II), Pt(II)(acac)₂,Pt(0)(PPh₃)₄, Pt(0)(DVTS) solution (CAS: 68478-92-2),Pt(0)(ethylene)(PPh₃)₂, Pt(II)Br₂(COD), tris(benzylideneacetone)Pt(0),Pt(II)(OAC)₂ solution, Pt(0)(t-Bu)₂, Pt(II)(COD)Me₂, Pt(II)(COD)I₂,Pt(IV)IMe₃ or Pt(II)(hexafluoroacetylacetonate)₂.
 8. The processaccording to claim 1, wherein the Pt compound is selected from:Pt(II)Br₂ or Pt(II)(acac)₂.
 9. The process according to claim 1, whereinthe bromine compound is selected from: Pt(II)Br₂ or LiBr.
 10. Theprocess according to claim 1, comprising the additional process stepe′): e′) adding a solvent.
 11. The process according to claim 10,wherein the solvent is selected from: THF, DCM, ACN, DMF, toluene,texanol, pentane, hexane, octane, isooctane, decane, dodecane,cyclohexane, benzene, xylene, Marlotherm, propylene carbonate, MTBE,diglyme, triglyme, diethyl ether, dioxane, isopropanol, tert-butanol,isononanol, isobutanol, isopentanol or ethyl acetate.
 12. The processaccording to claim 1, wherein CO and H₂ are fed in at a pressure in arange from 1 MPa (10 bar) to 6 MPa (60 bar).
 13. The process accordingto claim 1, wherein the reaction mixture is heated to a temperature inthe range from 25° C. to 150° C.
 14. The process according to claim 1,wherein the olefin is selected from: ethene, propene, 1-butene, cis-and/or trans-2-butene, isobutene, 1,3-butadiene, 1-pentene, cis- and/ortrans-2-pentene, 2-methyl-1-butene, 3-methyl-1-butene,2-methyl-2-butene, hexene, tetramethylethylene, heptene, 1-octene,2-octene, di-n-butene or mixtures thereof.